The invention relates to a nonferrous metallurgical process and reactor, and more specifically, to a floating entrainment metallurgical process and reactor.
In the nonferrous metal industry, pyrometallurgy refers to a process of obtaining nonferrous metals by removing the sulfur and iron in the sulfide ore by reacting the ore with oxygen. With the development of the metallurgical industry, progress of technology, as well as higher requirements for environmental protection, how to strengthen the smelting process and reduce production cost has become an important subject in the metallurgical industry, thus promoting new metallurgical processes to emerge continuously. Though following the same chemical reaction mechanism, pyrometallurgy can be roughly divided into two general types of processes: bath smelting and spatial suspension smelting, of which spatial suspension smelting is most widely applied in the Outokumpu Flash Smelting invented by Finnish scientists in 1949. In essence, spatial suspension smelting is intended to fully combine the material particles with the oxygen on the huge surface area of powder sulfide deposit after drying to realize instant oxidation (within 2 or 3 s), thus achieving desulfurization. During oxidation, an enormous amount of heat is generated, and the products, i.e. flue gas and melt, are at a high temperature, which means that the reaction furnace needs to bear an enormous heat load. Currently, a widely recognized suspension smelting furnace can stand a thermal load of up to 2000 MJ/m3·h, but higher thermal loads will severely erode and corrode the furnace lining.
Spatial suspension smelting is a continuous production process, in which the material and oxygen are continuously added in proportion with the calculated results for metallurgy. It is required that the materials and corresponding oxygen are fully combined and reacted in the metallurgical furnace within a limited space and time, otherwise, raw materials might flow out and peroxidation might occur. According to the already known methods described in CN1232538A (International publication No.: WO98/14741, Apr. 9, 1998), GB1569813, U.S. Pat. No. 5,133,801, U.S. Pat. No. 4,392,885, U.S. Pat. No. 5,362,032, U.S. Pat. No. 5,370,369, FI932458 and JP5-9613, the reaction gas is fed into the reaction furnace vertically from the lateral of the material flow, and the vertically dropped material is imported into the reaction gas by the distributor set on the center of the material flow and the diffused air in the horizontal direction, thus obtaining a suspended state. In these methods, the materials and reaction gas are kept away from the central axis and run towards the furnace wall until filling the entire space of the reaction furnace. What's to mention is that the furnace lining of the reactor will be greatly eroded and corroded by the high temperature during reaction and high-temperature melts directly, which requires the lining to favorable perform under enormous thermal load. Additionally, granularity and proportion of the materials are not completely equivalent, which makes it impossible to obtain an even distribution of the materials in the reaction gas. Areas with fewer materials might be exposed to excessive oxygen and the materials will be peroxided; while areas with more materials might lack enough oxygen and the materials shall be under the level of oxidation, resulting in raw materials that will not be oxidized.
In order to solve the above deficiencies, China patent (03125473) describes a spatial smelting method using a central rotating column: the dried powder material and oxygen are tangentially fed in through the burner set on the top center of the reaction shaft. Consisting of a number of concentric circular vortex chambers, an air chamber forms along the outside part of the concentrate chute; the inside part of the concentrate chute is equipped with an umbelliform dispersing cone, which is horizontally set with injection holes. In this process, the reaction gas remains at the outer surface of the material, therefore, it's necessary to use the gas jetted from the dispersing cone in the center of the material and the injection holes to mix the material and the reaction gas; the reaction gas passes through the vortex chamber into the high-temperature reaction shaft, and is expanded in volume by heating. Smaller amounts of jetted gas may result in the materials and the reaction gas failing to mix, while larger amounts of gas may destroy the vortex, thus making the materials and the reaction gas spread to the wall of the reaction shaft along the tangent direction. Moreover, injection holes are easily blocked and lose their function once in contact with the materials, and the cyclic non-contact transition collar will lower the utilization rate of oxygen, wherein the oxygen enters into the process equipment after the reaction furnace together with the furnace gas, and reacts with SO2, which generates sulfuric acid during cooling that further corrodes the equipment.
Similarly, China patent (Patent No.: ZL200910230500.3) describes that the dried materials and oxygen-enriched air are fed into a burner respectively, and are mixed to form a gas-solid two-phase mixture, which is rotated into the reactor at a high speed by a cyclone mounted in the burner, to form a rotary fluid with the axis as the center. In order to improve the probability of collisions between particles and to increase the amount of oxygen in the center of the rotary fluid, a pulser is further provided in the center of the nozzle to feed the oxygen or oxygen-enriched air into the rotary fluid by pulses.
Gas-solid two-phase mixture can also be available by this process, but a high rotating speed might be required to maintain the mixture in the reaction furnace. Gas-solid two-phase mixture at high rotating speed might cause serious abrasion to the burner and cyclone, which might result in failure of the burner in a short period. The pulsating oxygen or oxygen-enriched air is fed into the center of the rotary fluid and it is judged from the section of the rotating fluid whether the vortex core actually is a cavity with no materials or a few materials. Moreover, the pulsating feeding of oxygen or oxygen-enriched air makes the center materials fall too fast and down to the bottom without reaction. In addition, the change of the center oxygen potential causes a change in the reaction time and space, and increases the collision probability among particles, while simultaneously causing a fluctuation of the flue gas, or even results in resonance of the exhaust equipment, such as a waste heat boiler. The materials can form a gas-solid two-phase mixture before entering the reaction furnace, and consequently, the material particles can only be heated by high temperature radiation in the furnace and it take too long to reach the ignition point.